13bisfosfoglyseraatin

13bisfosfoglyseraatin, commonly referred to as **1,3-bisphosphoglycerate** (1,3-BPG), is an intermediate compound in the glycolytic pathway, a series of reactions that break down glucose to produce energy in the form of adenosine triphosphate (ATP). It plays a critical role in cellular respiration, particularly in the energy-producing phase of glycolysis known as the payoff phase.

During glycolysis, glucose is metabolized through a series of enzymatic reactions. In the third step of this pathway, the enzyme phosphoglycerate kinase catalyzes the conversion of 3-phosphoglycerate into 1,3-bisphosphoglycerate by transferring a phosphate group from 1,7-diphosphoglycerate (an earlier intermediate). This reaction is highly exergonic, meaning it releases a significant amount of energy, which is then used to phosphorylate adenosine diphosphate (ADP) into ATP, producing the first ATP molecule of glycolysis.

1,3-bisphosphoglycerate is also a substrate for the enzyme phosphoglycerate mutase, which converts it into 2,3-bisphosphoglycerate (2,3-BPG). In red blood cells, 2,3-BPG plays a regulatory role by modulating the affinity of hemoglobin for oxygen, influencing oxygen delivery to tissues. However, in most other cells, 2,3-BPG is a minor intermediate, and the primary role of 1,3-bisphosphoglycerate remains in ATP production.

The structure of 1,3-bisphosphoglycerate consists of a three-carbon glycerol backbone with phosphate groups attached to the first and third carbons. Its high-energy phosphate bonds make it a key molecule in energy transfer within the cell. The compound is found in all living organisms that utilize glycolysis for energy production, highlighting its fundamental importance in cellular metabolism.